1. Field of the Invention
The present invention relates to a field of electric connector, and in particular, to a structure for a terminal of an electric connector.
2. Description of the Related Art
It has been known that in an electric connector in the prior art, the terminal sheet generally provides a locking force or a retention force for the connection or the contact between the terminals sheet. In general, the terminal sheet usually adopts a cantilevered beam structure, such as a beam.
With the reference of FIG. 1a and FIG. 1b, they schematically illustrate the characteristics of the beam structure. FIG. 1a shows a basic mechanical schematic view of a cantilever beam having one fixed end, meanwhile a flexural moment distribution map of the cantilever beam with one end under an external force F is shown. As shown in FIG. 1a, the fixed end of the beam bears the maximum flexural moment T. And, FIG. 1b shows the continuous stress distribution on the whole beam under the external force F, in which the fixed end of this beam bears a maximum stress. From these figures, based on the mechanical characteristics of the beam structure, the fixed end of the beam bears the maximum flexural moment, accordingly, the deformation tolerance and the endurance stress limit of the whole beam depend on the endurance stress limit of the fixed end of the beam.
According to the above-mentioned mechanical principle of the cantilevered beam, there is an uneven stress distribution on an ideal beam of constant cross-section (as shown in FIG. 2a), that is to say, some parts of this ideal beam are useless for the stress. In an electric connector, the thickness of the beam-type terminal sheet usually remains unchanged because the terminal is made of a single piece of sheet-metal material. That is to say, it is unfeasible to change the stress distribution on the beam-type terminal sheet by varying the thickness of such terminal sheet.
Furthermore, in the design of this beam, the even stress distribution may be achieved by varying the width of such beam (as shown in FIG. 2b). This, however, improves merely the tolerance, of deformation of the beam, without helping to improve the stress characteristics of the beam. At the same time, in an electric connector, the beam-type terminal sheet should have certain width to ensure enough contact area to form a stable electrical connection. Therefore, there is a contradiction between reducing the width of the free end of the beam and increasing effective contact area of the terminal. Thus, it is also unfeasible to adopt the above-mentioned method of improving the stress distribution on the beam by varying the width of such beam in the electric connector.